title: A fragment of the Xanthomonas oryzae pv. oryzicola harpin HpaG Xooc reduces disease and increases yield of rice in extensive grower plantings.
abstract: Harpins of phytopathogenic bacteria stimulate defense and plant growth in many types of plants, conferring disease resistance and enhanced yield. In a previous study, we characterized nine fragments of the harpin protein HpaG(Xooc) from Xanthomonas oryzae pv. oryzicola for plant defense elicitation and plant growth stimulation activity relative to the intact protein. In plants grown under controlled conditions, the fragment HpaG10-42 was more active in both regards than HpaG(Xooc). Here, we demonstrate that the activity of HpaG10-42 in rice under field conditions significantly exceeds that of HpaG(Xooc), stimulating resistance to three important diseases and increasing grain yield. We carried out tests in 672 experimental plots with nine cultivars of rice planted at three locations. Application protocols were optimized by testing variations in application rate, frequency, and timing with respect to rice growth stage. Of the concentrations (24, 24, 12, and 6 microg/ml), and number and timing of applications (at one to four different stages of growth) tested, HpaG10-42 at 6 microg/ml applied to plants once at nursery seedling stage and three times in the field was most effective. Bacterial blight, rice blast, and sheath blight were reduced 61.6 and 56.4, 93.6 and 76.0, and 93.2 and 55.0% in indica and japonica cultivars, respectively, relative to controls. Grain yields were 22 to 27% greater. These results are similar to results obtained with typical local management practices, including use of chemicals, to decrease disease severities and increase yield in rice. Our results demonstrate that the HpaG10-42 protein fragment can be used effectively to control diseases and increase yield of this staple food crop.
authors.affiliation: Plant Growth and Defense Signaling Laboratory, Group of Key Laboratory of Monitoring and Management of Plant Pathogens and Insect Pests, Ministry of Agriculture of P.R. China, Nanjing Agricultural University, Nanjing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Shu-Jian
authors.initials: SJ
authors.lastname: Zhang
authors.forename: Shao-Song
authors.initials: SS
authors.lastname: Zhang
authors.forename: Shuping
authors.initials: S
authors.lastname: Qu
authors.forename: Xiuyan
authors.initials: X
authors.lastname: Ren
authors.forename: Juying
authors.initials: J
authors.lastname: Long
authors.forename: Qian
authors.initials: Q
authors.lastname: Yin
authors.forename: Jun
authors.initials: J
authors.lastname: Qian
authors.forename: Feng
authors.initials: F
authors.lastname: Sun
authors.forename: Chunling
authors.initials: C
authors.lastname: Zhang
authors.forename: Lingxian
authors.initials: L
authors.lastname: Wang
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Wu
authors.forename: Tingquan
authors.initials: T
authors.lastname: Wu
authors.forename: Zhongkai
authors.initials: Z
authors.lastname: Zhang
authors.forename: Zaiquan
authors.initials: Z
authors.lastname: Cheng
authors.forename: Marshall
authors.initials: M
authors.lastname: Hayes
authors.forename: Steven V
authors.initials: SV
authors.lastname: Beer
authors.forename: Hansong
authors.initials: H
authors.lastname: Dong
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism / Q000494:pharmacology*; D002681:China; D005843:Geography; D007113:Immunity, Innate / Q000187:drug effects; D012275:Oryza / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology*; D014974:Xanthomonas / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; C075462:harpin protein, Erwinia amylovora